Re: Sewing a Hakama ..?
I've also done two black hakama by myself. No pattern, used the width of the fabric for the width of one leg. Fabric was viscose-polyester-blend twill. The second was even a bit elastic... (liked this after a little while). For the koshita I experimented with various things but best (in my opinion) is, as already mentioned, a thick rubber plate (seal plate?).
I've both worn until the knees split and one is now patched and serves as my spare hakama. I have to admit the one I'm wearing currently I bought. but only because I got the chance to go to Tozandos in Kyoto. They are much cheaper there than over here in Germany.... (but only if you don't count the costs of the trip... ;-))